Related papers: Prospects for detecting an $\eta_c'$ in two photon…
The recently discovered enhancement of eta photoproduction on the quasi-free neutron at energies around s^1/2 ~ 1.67 GeV is addressed within an SU(3) coupled channels model. The K Sigma threshold plays a significant role and the quasi-free…
We study the radiative decays of the $Z_c(3900)^0$ in a hadronic molecule picture, where the $Z_c(3900)$ is treated as a $D \bar{D}^\ast +c.c$ hadronic molecule. The partial widths of $\Gamma(Z_c(3900)^0 \to \gamma \eta_c(2S))$ and…
The hadronic decay $\eta_c(2S) \to 3(\pi^+\pi^-)$ is observed with a statistical significance of 9.3 standard deviations using $(448.1\pm2.9)\times10^6$ $\psi(3686)$ events collected by the BESIII detector at the BEPCII collider. The…
Using data acquired with the CLEO-c detector at the CESR e+e- collider, we measure branching fractions for J/psi, psi(2S), and psi(3770) decays to gamma pi0, gamma eta, and gamma eta'. Defining R_n = B[ psi(nS)-->gamma eta ]/B[…
The differential cross-section for the process e+e- -> \gamma\gamma is calculated assuming the presence of excited electrons with a chiral magnetic coupling. This calculation permits constraining the excited electron coupling using the same…
A new process of a nuclear excitation to discrete states in peripheral heavy ion collisions is studied. High energy photons are emitted by the exited nuclei with energies up to a few tens GeV at angles of a few hundred microradians with…
By analyzing $(27.12 \pm 0.14)\times10^{8}$ $\psi(3686)$ events accumulated with the BESIII detector, the decay $\eta_{c}(2S) \to K^{+} K^{-} \eta$ is observed for the first time with a significance of $6.2\sigma$ after considering…
We report a measurement of high-p_T inclusive pi^0, eta, and direct photon production in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi^0 -> gamma gamma were detected in the Barrel…
We present a theoretical estimation for the cross-section of exclusive two $\rho$-meson production in two photon collision when one of the initial photons is highly virtual. The compatibility of our analysis with recent experimental data…
Eta photo- and electroproduction off the nucleon is investigated in an effective lagrangian approach that contains Born terms and both vector meson and nucleon resonance contributions. In particular, we review and develop the formalism for…
Based on $(27.12\pm 0.14)\times 10^{8}$ $\psi(2S)$ events collected with the BESIII detector, we search for the decay $\eta_c (2S) \rightarrow \pi^{+} \pi^{-} \eta_c$ with $\eta_c\rightarrow K_S^0 K^{\pm}\pi^{\mp}$ and $\eta_c\rightarrow…
$\gamma (p,K^0)\Sigma^+$ cross section was measured at the CBELSA/TAPS experiment at the ELSA electron stretcher facility. A cusp-like structure was apparent near the $K^*$ production threshold, where the cross section reduced by a factor…
The eta(1760) may be significantly produced in J/Psi radiative decay. We deduce from experimental data that its branching ratio to two gluons is bounded, 0.4 +- 0.3 < BR(eta(1760) -> gg) < 0.9 +- 0.3, consistent with gluonic admixture.…
Using 12.7 $fb^{-1}$ of data collected with the CLEO detector at CESR, we observed two-photon production of the $c \bar c$ states $\chi_{c0}$ and $\chi_{c2}$ in their decay to $\pi^+ \pi^- \pi^+ \pi^-$. We measured…
Based on a sample of $(1310.6 \pm 7.0) \times 10^6~J/\psi$ events collected with the BESIII detector, we present measurements of $J/\psi$ and $\eta^\prime$ absolute branching fractions using the process $J/\psi\rightarrow\gamma\eta^\prime$.…
We study the $\eta$-photoproduction focusing on the new nucleon resonance which was observed at $\sqrt{s}=1675$ MeV with a narrow decay width ($\sim 10$ MeV) in the recent GRAAL experiment. Using an effective Lagrangian approach, we compute…
The cross section of the process e+ e- ---> eta gamma has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23)…
Coherent photoproduction of $\eta$-mesons off $^3$He, i.e. the reaction $\gamma ^3{He}\rightarrow \eta ^3{He}$, has been investigated in the near-threshold region. The experiment was performed at the Glasgow tagged photon facility of the…
We analyze the potential of TESLA and CLIC based electron-photon colliders to search for excited spin-1/2 electrons. The production of excited electrons in the resonance channel through the electron-photon collision and their subsequent…
Using a data sample of $1.31\times10^{9} ~J/\psi$ events collected with the BESIII detector, a search for $\eta'\to\gamma\gamma\eta$ via $J/\psi\to\gamma\eta'$ is performed for the first time. No significant $\eta'$ signal is observed in…